ABSTRACT Smoking is disproportionately prevalent among persons living with HIV (PLWH) as compared to the United States general population, increasingly contributing to high levels of morbidity and mortality in this population. Conventional smoking cessation modalities have low acceptability among PLWH, indicating the need to develop new and innovative strategies to improve cessation in this population. Mobile health (mHealth) holds promise as a tool to provide evidence-based smoking cessation interventions in the US population, with a majority of HIV-positive smokers owning a smartphone, and previous mHealth studies showing promise to treat tobacco dependence among PLWH. However, in a review of the empirical mHealth literature we found that rigorous early-phase studies of mHealth apps for smoking cessation are critically necessary to ensure the development of usable, acceptable and theory-based smoking cessation mHealth technology. In prior work we developed Learn to Quit (LTQ), an evidence-based smoking cessation app that combines a promising mindfulness-based intervention with U.S. Clinical Practice Guidelines. LTQ was tailored to persons living with chronic mental illness, a population that shares similar user-centered design challenges with PLWH (e.g., psychiatric symptoms, cognitive deficits). On that premise, we propose to develop LTQ-H, a rigorously designed smoking cessation app tailored to PLWH, and test it in a pilot randomized controlled trial. Our first aim is to: (1) form an expert panel to inform LTQ adaptations to PLWH, (2) conduct user-centered design research to ideate and test an LTQ-H prototype, (3) work with a software vendor to develop the LTQ-H app. Our second aim is to conduct a pilot randomized controlled trial to test the feasibility, acceptability and preliminary efficacy of LTQ-H, as well as its effects on HIV-specific outcomes. The proposed team -- Drs. Pacek, Vilardaga, McClernon -- has expertise in (1) tobacco dependence in PLWH, (2) smoking cessation mHealth development in medically vulnerable populations, (3) clinical trials, and (4) public health policy -- a much needed background to turn early-phase translational work into ?real world? implementation. The proposed work is consistent with the Trans-NIH Plan for HIV-Related Research (NOT-OD-15-137), incorporating state-of-the-art technology to improve access to hard-to-reach populations, and addressing HIV- associated comorbidities and complications. Data from these early-phase studies will inform the design of a larger R01-funded RCT and the necessary regulatory strategy to approve LTQ-H as a prescription device that could become standard of care of PLWH in clinical settings.